Metro Girl by Janet Evanovich

Metro Girl (Alex Barnaby Series #1) - Alexandra Barnaby, aka Barney, was raised in her father’s Baltimore garage.  She knows cars and engines, and has raced them as well. Bill, her younger brother, calls her from Miami to tell her he will be gone for a while and not to worry, however, the phone connection is broken off right after a woman screams.  Alex, goes to Miami to find Bill, meets Sam Hooker, NASCAR guy, and the owner of the boat Bill has “borrowed.”  During her investigation, Alex and Sam run into Cuban guys who are also looking for Bill, because he has something that belongs to their boss.